import hashlib
import os
import urllib
import warnings
from typing import Any, Union, List
from torch import nn
import torch
from PIL import Image
from torchvision.transforms import Compose, Resize, CenterCrop, ToTensor, Normalize
from tqdm import tqdm
from safetensors.torch import load_file

from .model_longclip import build_model
from .simple_tokenizer import SimpleTokenizer as _Tokenizer

try:
    import packaging
except ImportError:
    from pkg_resources import packaging

try:
    from torchvision.transforms import InterpolationMode
    BICUBIC = InterpolationMode.BICUBIC
except ImportError:
    BICUBIC = Image.BICUBIC


if packaging.version.parse(torch.__version__) < packaging.version.parse("1.7.1"):
    warnings.warn("PyTorch version 1.7.1 or higher is recommended")


__all__ = ["load", "tokenize"]
_tokenizer = _Tokenizer()


def _convert_image_to_rgb(image):
    return image.convert("RGB")


def _transform(n_px):
    return Compose([
        Resize(n_px, interpolation=BICUBIC),
        CenterCrop(n_px),
        _convert_image_to_rgb,
        ToTensor(),
        Normalize((0.48145466, 0.4578275, 0.40821073), (0.26862954, 0.26130258, 0.27577711)),
    ])



def load(name: str, device: Union[str, torch.device] = "cuda" if torch.cuda.is_available() else "cpu", download_root: str = None):
    """Load a long CLIP model

    Parameters
    ----------
    name : str
        A model name listed by `clip.available_models()`, or the path to a model checkpoint containing the state_dict

    device : Union[str, torch.device]
        The device to put the loaded model

    Returns
    -------
    model : torch.nn.Module
        The CLIP model

    preprocess : Callable[[PIL.Image], torch.Tensor]
        A torchvision transform that converts a PIL image into a tensor that the returned model can take as its input
    """
    
    model_path = name

    if model_path.endswith(".safetensors"):
        state_dict = load_file(model_path, device="cpu")
    else:
        state_dict = torch.load(model_path, map_location="cpu")
    
    model = build_model(state_dict or model.state_dict(), load_from_clip=False).to(device)

    if str(device) == "cpu":
        model.float()

    return model, _transform(model.visual.input_resolution)
        
    

    def _node_get(node: torch._C.Node, key: str):
        """Gets attributes of a node which is polymorphic over return type.
        
        From https://github.com/pytorch/pytorch/pull/82628
        """
        sel = node.kindOf(key)
        return getattr(node, sel)(key)

    def patch_device(module):
        try:
            graphs = [module.graph] if hasattr(module, "graph") else []
        except RuntimeError:
            graphs = []

        if hasattr(module, "forward1"):
            graphs.append(module.forward1.graph)

        for graph in graphs:
            for node in graph.findAllNodes("prim::Constant"):
                if "value" in node.attributeNames() and str(_node_get(node, "value")).startswith("cuda"):
                    node.copyAttributes(device_node)

    model.apply(patch_device)
    patch_device(model.encode_image)
    patch_device(model.encode_text)

    # patch dtype to float32 on CPU
    if str(device) == "cpu":
        float_holder = torch.jit.trace(lambda: torch.ones([]).float(), example_inputs=[])
        float_input = list(float_holder.graph.findNode("aten::to").inputs())[1]
        float_node = float_input.node()

        def patch_float(module):
            try:
                graphs = [module.graph] if hasattr(module, "graph") else []
            except RuntimeError:
                graphs = []

            if hasattr(module, "forward1"):
                graphs.append(module.forward1.graph)

            for graph in graphs:
                for node in graph.findAllNodes("aten::to"):
                    inputs = list(node.inputs())
                    for i in [1, 2]:  # dtype can be the second or third argument to aten::to()
                        if _node_get(inputs[i].node(), "value") == 5:
                            inputs[i].node().copyAttributes(float_node)

        model.apply(patch_float)
        patch_float(model.encode_image)
        patch_float(model.encode_text)

        model.float()

    return model, _transform(model.input_resolution.item())


def load_from_clip(name: str, device: Union[str, torch.device] = "cuda" if torch.cuda.is_available() else "cpu", jit: bool = False, download_root: str = None):
    """Load from CLIP model for fine-tuning 

    Parameters
    ----------
    name : str
        A model name listed by `clip.available_models()`, or the path to a model checkpoint containing the state_dict

    device : Union[str, torch.device]
        The device to put the loaded model

    jit : bool
        Whether to load the optimized JIT model or more hackable non-JIT model (default).

    download_root: str
        path to download the model files; by default, it uses "~/.cache/clip"

    Returns
    -------
    model : torch.nn.Module
        The CLIP model

    preprocess : Callable[[PIL.Image], torch.Tensor]
        A torchvision transform that converts a PIL image into a tensor that the returned model can take as its input
    """

    _MODELS = {
    "RN50": "https://openaipublic.azureedge.net/clip/models/afeb0e10f9e5a86da6080e35cf09123aca3b358a0c3e3b6c78a7b63bc04b6762/RN50.pt",
    "RN101": "https://openaipublic.azureedge.net/clip/models/8fa8567bab74a42d41c5915025a8e4538c3bdbe8804a470a72f30b0d94fab599/RN101.pt",
    "RN50x4": "https://openaipublic.azureedge.net/clip/models/7e526bd135e493cef0776de27d5f42653e6b4c8bf9e0f653bb11773263205fdd/RN50x4.pt",
    "RN50x16": "https://openaipublic.azureedge.net/clip/models/52378b407f34354e150460fe41077663dd5b39c54cd0bfd2b27167a4a06ec9aa/RN50x16.pt",
    "RN50x64": "https://openaipublic.azureedge.net/clip/models/be1cfb55d75a9666199fb2206c106743da0f6468c9d327f3e0d0a543a9919d9c/RN50x64.pt",
    "ViT-B/32": "https://openaipublic.azureedge.net/clip/models/40d365715913c9da98579312b702a82c18be219cc2a73407c4526f58eba950af/ViT-B-32.pt",
    "ViT-B/16": "https://openaipublic.azureedge.net/clip/models/5806e77cd80f8b59890b7e101eabd078d9fb84e6937f9e85e4ecb61988df416f/ViT-B-16.pt",
    "ViT-L/14": "https://openaipublic.azureedge.net/clip/models/b8cca3fd41ae0c99ba7e8951adf17d267cdb84cd88be6f7c2e0eca1737a03836/ViT-L-14.pt",
    "ViT-L/14@336px": "https://openaipublic.azureedge.net/clip/models/3035c92b350959924f9f00213499208652fc7ea050643e8b385c2dac08641f02/ViT-L-14-336px.pt",
    }

    def available_models() -> List[str]:
        """Returns the names of available CLIP models"""
        return list(_MODELS.keys())

    def _download(url: str, root: str):
        os.makedirs(root, exist_ok=True)
        filename = os.path.basename(url)

        expected_sha256 = url.split("/")[-2]
        download_target = os.path.join(root, filename)

        if os.path.exists(download_target) and not os.path.isfile(download_target):
            raise RuntimeError(f"{download_target} exists and is not a regular file")

        if os.path.isfile(download_target):
            if hashlib.sha256(open(download_target, "rb").read()).hexdigest() == expected_sha256:
                return download_target
            else:
                warnings.warn(f"{download_target} exists, but the SHA256 checksum does not match; re-downloading the file")

        with urllib.request.urlopen(url) as source, open(download_target, "wb") as output:
            with tqdm(total=int(source.info().get("Content-Length")), ncols=80, unit='iB', unit_scale=True, unit_divisor=1024) as loop:
                while True:
                    buffer = source.read(8192)
                    if not buffer:
                        break

                    output.write(buffer)
                    loop.update(len(buffer))

        if hashlib.sha256(open(download_target, "rb").read()).hexdigest() != expected_sha256:
            raise RuntimeError("Model has been downloaded but the SHA256 checksum does not not match")

        return download_target

    if name in _MODELS:
        model_path = _download(_MODELS[name], download_root or os.path.expanduser("~/.cache/clip"))
    elif os.path.isfile(name):
        model_path = name
    else:
        raise RuntimeError(f"Model {name} not found; available models = {available_models()}")

    with open(model_path, 'rb') as opened_file:
        try:
            # loading JIT archive
            model = torch.jit.load(opened_file, map_location=device if jit else "cpu").eval()
            state_dict = None
        except RuntimeError:
            # loading saved state dict
            if jit:
                warnings.warn(f"File {model_path} is not a JIT archive. Loading as a state dict instead")
                jit = False
            state_dict = torch.load(opened_file, map_location="cpu")

    model = build_model(state_dict or model.state_dict(), load_from_clip = True).to(device)
        
    positional_embedding_pre = model.positional_embedding.type(model.dtype)
            
    length, dim = positional_embedding_pre.shape
    keep_len = 20
    posisitonal_embedding_new = torch.zeros([4*length-3*keep_len, dim], dtype=model.dtype)
    for i in range(keep_len):
        posisitonal_embedding_new[i] = positional_embedding_pre[i]
    for i in range(length-1-keep_len):
        posisitonal_embedding_new[4*i + keep_len] = positional_embedding_pre[i + keep_len]
        posisitonal_embedding_new[4*i + 1 + keep_len] = 3*positional_embedding_pre[i + keep_len]/4 + 1*positional_embedding_pre[i+1+keep_len]/4
        posisitonal_embedding_new[4*i + 2+keep_len] = 2*positional_embedding_pre[i+keep_len]/4 + 2*positional_embedding_pre[i+1+keep_len]/4
        posisitonal_embedding_new[4*i + 3+keep_len] = 1*positional_embedding_pre[i+keep_len]/4 + 3*positional_embedding_pre[i+1+keep_len]/4

    posisitonal_embedding_new[4*length -3*keep_len - 4] = positional_embedding_pre[length-1] + 0*(positional_embedding_pre[length-1] - positional_embedding_pre[length-2])/4
    posisitonal_embedding_new[4*length -3*keep_len - 3] = positional_embedding_pre[length-1] + 1*(positional_embedding_pre[length-1] - positional_embedding_pre[length-2])/4
    posisitonal_embedding_new[4*length -3*keep_len - 2] = positional_embedding_pre[length-1] + 2*(positional_embedding_pre[length-1] - positional_embedding_pre[length-2])/4
    posisitonal_embedding_new[4*length -3*keep_len - 1] = positional_embedding_pre[length-1] + 3*(positional_embedding_pre[length-1] - positional_embedding_pre[length-2])/4
            
    positional_embedding_res = posisitonal_embedding_new.clone()
            
    model.positional_embedding = nn.Parameter(posisitonal_embedding_new, requires_grad=False)
    model.positional_embedding_res = nn.Parameter(positional_embedding_res, requires_grad=True)

    if str(device) == "cpu":
        model.float()
    return model, _transform(model.visual.input_resolution)
        
    def _node_get(node: torch._C.Node, key: str):
        """Gets attributes of a node which is polymorphic over return type.
        
        From https://github.com/pytorch/pytorch/pull/82628
        """
        sel = node.kindOf(key)
        return getattr(node, sel)(key)

    def patch_device(module):
        try:
            graphs = [module.graph] if hasattr(module, "graph") else []
        except RuntimeError:
            graphs = []

        if hasattr(module, "forward1"):
            graphs.append(module.forward1.graph)

        for graph in graphs:
            for node in graph.findAllNodes("prim::Constant"):
                if "value" in node.attributeNames() and str(_node_get(node, "value")).startswith("cuda"):
                    node.copyAttributes(device_node)

    model.apply(patch_device)
    patch_device(model.encode_image)
    patch_device(model.encode_text)

    # patch dtype to float32 on CPU
    if str(device) == "cpu":
        float_holder = torch.jit.trace(lambda: torch.ones([]).float(), example_inputs=[])
        float_input = list(float_holder.graph.findNode("aten::to").inputs())[1]
        float_node = float_input.node()

        def patch_float(module):
            try:
                graphs = [module.graph] if hasattr(module, "graph") else []
            except RuntimeError:
                graphs = []

            if hasattr(module, "forward1"):
                graphs.append(module.forward1.graph)

            for graph in graphs:
                for node in graph.findAllNodes("aten::to"):
                    inputs = list(node.inputs())
                    for i in [1, 2]:  # dtype can be the second or third argument to aten::to()
                        if _node_get(inputs[i].node(), "value") == 5:
                            inputs[i].node().copyAttributes(float_node)

        model.apply(patch_float)
        patch_float(model.encode_image)
        patch_float(model.encode_text)

        model.float()

    return model, _transform(model.input_resolution.item())

def only_tokenize(texts: Union[str, List[str]]) -> Union[torch.IntTensor, torch.LongTensor]:
    if isinstance(texts, str):
        texts = [texts]

    sot_token = _tokenizer.encoder["<|startoftext|>"]
    eot_token = _tokenizer.encoder["<|endoftext|>"]
    all_tokens = [[sot_token] + _tokenizer.encode(text) + [eot_token] for text in texts]
    return all_tokens

def tokenize(texts: Union[str, List[str]], context_length: int = 77*4-60, truncate: bool = False) -> Union[torch.IntTensor, torch.LongTensor]:
    """
    Returns the tokenized representation of given input string(s)

    Parameters
    ----------
    texts : Union[str, List[str]]
        An input string or a list of input strings to tokenize

    context_length : int
        The context length to use; all CLIP models use 77 as the context length

    truncate: bool
        Whether to truncate the text in case its encoding is longer than the context length

    Returns
    -------
    A two-dimensional tensor containing the resulting tokens, shape = [number of input strings, context_length].
    We return LongTensor when torch version is <1.8.0, since older index_select requires indices to be long.
    """
    if isinstance(texts, str):
        texts = [texts]

    sot_token = _tokenizer.encoder["<|startoftext|>"]
    eot_token = _tokenizer.encoder["<|endoftext|>"]
    all_tokens = [[sot_token] + _tokenizer.encode(text) + [eot_token] for text in texts]
    if packaging.version.parse(torch.__version__) < packaging.version.parse("1.8.0"):
        result = torch.zeros(len(all_tokens), context_length, dtype=torch.long)
    else:
        result = torch.zeros(len(all_tokens), context_length, dtype=torch.int)

    for i, tokens in enumerate(all_tokens):
        if len(tokens) > context_length:
            if truncate:
                tokens = tokens[:context_length]
                tokens[-1] = eot_token
            else:
                raise RuntimeError(f"Input {texts[i]} is too long for context length {context_length}")
        result[i, :len(tokens)] = torch.tensor(tokens)

    return result
